Not Applicable
Not Applicable
1. Technical Field
This invention relates to methods of manufacturing films for incorporation as backing layers in resilient floor coverings, to films made by such methods and to floor coverings incorporating them.
2. Background Art
Resilient floor coverings are well known and are described for example in an article entitled xe2x80x9cFloor Materialsxe2x80x9d in Encyclopedia of Polymer Science and Engineering, Wiley-Interscience, Volume 7 (1987), pages 223-247. Such floor coverings, as described in that article, are composite materials which comprise a transparent or translucent wear (upper) layer, often a decorative (intermediate) layer such as a printed patterned layer, and one or more backing (lower) layers. The composition of each layer in such composite laminate floor coverings is chosen to provide the desired balance of physical properties, both in that layer and in the whole composite laminate. Thus, for example, the properties of all the layers are desirably balanced so as to avoid curl.
The backing layer nearest the wear layer commonly contains one or more colored pigments and is commonly called the face ply. If no intermediate decorative layer is present, then the face ply itself provides the desired decorative appearance of the floor covering. If the floor covering includes a printed patterned layer, then the face ply serves to enhance the appearance of the printed patterned layer as seen through the wear layer. The face ply is often of a bright color, for example white, although it may be of a neutral color such as black. The other backing layers more remote from the wear layer commonly contain carbon black to provide a neutral opaque background behind the face ply. All the backing layers, including the face ply, commonly contain fillers such as calcium carbonate, hydrated aluminum oxide, kaolin or other suitable particulate or fibrous mineral fillers.
Films for incorporation in resilient floor coverings may be made by extrusion of suitable polymer compositions. For example, the backing layers including the face ply may be made by extrusion of polymer compositions based on ethylene/vinyl acetate or ethylene/alkyl acrylate, for example methyl or butyl acrylate, copolymers. It is often desirable to make differently-colored face plies at different times on a single extruder. Steps must therefore be taken to minimize the production of waste film at changeover. The extruder may be stopped, emptied and cleaned, but this is laborious and involves loss of production from the extruder while this is done. Alternatively, the color of the polymer composition fed to the extruder may be changed while the extruder continues to run, and waste film of intermediate color may be collected until the extruder has been flushed. This waste film can be shredded and used (with the addition of carbon black, if desired) for the manufacture of black backing layers. Nevertheless, this procedure requires additional operations to be carried out, and these operations may result in some degradation of properties of the thus recycled polymer composition.
The present invention provides improved methods of manufacturing a film for incorporation as a backing layer in resilient floor coverings, in particular to a method for manufacturing a film which includes a face ply where loss of production is reduced when the color of a face ply is changed.
The present invention provides in a first aspect a method of manufacturing a film for incorporation as a backing layer in a resilient floor covering characterized in that at least a first and a second polymer composition are extruded to form a film laminate for use as the backing layer.
Preferably where there are two polymer compositions, a first polymer composition and a second polymer composition, the first polymer composition is a colored polymer composition. The second polymer composition may be colored a masking color such as black, iron-oxide red, blue, or any dark masking color.
There may be three polymer layers extruded to form the film. Preferably when there are three polymer compositions, a first, a second and a third polymer composition, the first and/or third polymer compositions are colored polymer compositions and the second layer/composition is of masking color. The second polymer composition may also be a colored polymer composition.
Preferably the second polymer composition of both systems is a xe2x80x9cblackxe2x80x9d polymer composition. xe2x80x9cBlackxe2x80x9d in the context of this specification includes true black, dark red, dark blue, or any color capable of masking the presence of other colors.
When the backing layer is a face ply the color of the colored polymer composition is chosen to provide the face ply color, and it will accordingly be understood that this color may be any color, including black, or including lighter colors such as white, yellow, beige, pale greens or blues, pink.
The invention provides in a second aspect a film suitable for incorporation as a backing layer in a resilient floor covering characterized in that it is a co-extruded laminate of at least two polymer compositions.
Preferably where there are two polymer compositions the film is a co-extruded laminate of (a) a first colored polymer composition and (b) a xe2x80x9cblackxe2x80x9d polymer composition.
Preferably where there are three polymer compositions the film is a co-extruded laminate of (a) a first colored polymer composition, (b) a xe2x80x9cblackxe2x80x9d polymer composition and (c) a third polymer composition.
The invention provides in a third aspect a resilient floor covering comprising a transparent or translucent wear layer and a backing layer characterized in that the backing layer comprises, in sequential order from the wear layer, at least one backing film which is a co-extruded laminate of at least two polymer compositions.
The floor covering may comprise a transparent or translucent wear layer and two (or more) backing layers, or plys. Preferably where there are two polymer compositions the backing layer comprises in sequential order from the wear layer (a) a first backing film which is a co-extruded laminate of (aa) a first colored polymer composition visible as face ply through the wear layer and (ab) a xe2x80x9cblackxe2x80x9d polymer composition, and (b) a second backing film of substantially the same thickness as the first backing film.
The first colored polymer composition (aa) may be of any color, including black. The second backing film (b) may be a co-extruded laminate of (ba) a second colored polymer composition and (bb) a xe2x80x9cblackxe2x80x9d polymer composition. The second colored polymer composition (ba) may be of any color, including black. Layers (aa) and (ba) are preferably of substantially the same thickness, with the consequence that layers (ab) and (bb) are also preferably of substantially the same thickness. The floor covering of the invention preferably additionally comprises a printed patterned layer as decorative layer interposed between the wear layer and the first backing film.
Preferably where there are three polymer compositions the backing layer comprises in sequential order from the wear layer (a) a first backing film which is a co-extruded laminate of (aa) a first colored polymer composition visible as face ply through the wear layer (ab) a xe2x80x9cblackxe2x80x9d polymer composition, and (ac) a third polymer composition.
Preferably a second backing film (b) is provided.
The first colored polymer composition (aa) may be of any color including black. The third polymer composition (ac) may be of any color including black. The second backing film (b) may be a co-extruded laminate of (ba) a second colored polymer composition (bb) a xe2x80x9cblackxe2x80x9d polymer composition and (bc) a third polymer composition. The second colored polymer composition (ba) may be of any color, including black. The third polymer composition (bc) may be of any color including black. Layers (aa) and (ba) are preferably of substantially the same thickness, with the consequence that layers (ab) and (bb) are also preferably of substantially the same thickness as are layer (ac) and (bc). The floor covering of the invention preferably additionally comprises a printed patterned layer as decorative layer interposed between the wear layer and the first backing film.
The invention provides in a fourth aspect a method of manufacturing a resilient floor covering, including the steps of:
(i) co-extruding at least two polymer compositions to form a laminate to serve as a first backing film; and
(ii) laminating together in sequential order (a) a transparent or translucent wear layer, and (b) at least one backing film, whereby the first polymer composition is visible through the wear layer.
Preferably where there are two polymer compositions the method of manufacturing a resilient floor covering, includes the steps of:
(i) co-extruding a first colored polymer composition and a black polymer composition to form a laminate to serve as first backing film; and
(ii) laminating together in sequential order (a) a transparent or translucent wear layer, (b) the first backing film and (c) a second backing film of substantially the same thickness as the first backing film, whereby the colored polymer composition is visible through the wear layer.
The first colored polymer composition may be of any color, including black. Preferably, a decorative layer such as a printed patterned layer is interposed between the wear layer (a) and the first backing film (b) prior to the lamination step (ii). The second backing film may be co-extruded laminate of a second colored polymer composition and a xe2x80x9cblackxe2x80x9d polymer composition, wherein the second colored polymer composition may be of any color, including black.
Preferably where there are three polymer compositions the method of manufacturing a resilient floor covering, includes the steps of:
(i) co-extruding a first colored polymer composition, a xe2x80x9cblackxe2x80x9d polymer composition and a third polymer composition to form a laminate to serve as first backing film; and
(ii) laminating together in sequential order (a) a transparent or translucent wear layer, (b) at least one backing film, whereby the colored polymer composition is visible through the wear layer.
Preferably a second backing film of substantially the same thickness as the first backing film is provided.
The first colored polymer composition and the third polymer composition may be of any color, including black. Preferably, a decorative layer such as a printed patterned layer is interposed between the wear layer (a) and the first backing film (b) prior to the lamination step (ii). The second backing film may be a co-extruded laminate of a second colored polymer composition, a xe2x80x9cblackxe2x80x9d polymer composition and a third polymer composition, wherein the second colored polymer composition and the third polymer composition may be of any color, including black.
The invention provides in a fifth aspect a method of reducing the amount of waste produced when the color of a face ply is changed in a resilient floor covering having a wear layer and a backing layer comprising at least one backing film wherein said backing film comprises a laminate formed from at least a first and a second polymer composition comprising the steps of:
(i) changing the formulation of the first polymer composition in the laminate to provide a new color whereby the color changes through intermediate shades from an original colored polymer composition to a new colored polymer composition; and
(ii) using the intermediately colored laminate in the backing layer of the resilient floor covering wherein the intermediately colored polymer composition is positioned away from the wear layer in that it is not visible therethrough.
Preferably when the color of the face ply is changed in a resilient floor covering having two backing layers the method comprises the steps of:
(i) co-extruding at least a first polymer composition and a xe2x80x9cblackxe2x80x9d polymer composition to form a laminate to serve as a first backing film;
(ii) changing the formulation of the first colored polymer composition in the laminate to provide a new color whereby the color changes through intermediate shades from the original colored composition to the new polymer composition while the original color is flushed out; and
(iii) using the intermediately colored laminate as the second backing film in a resilient floor covering which sequentially comprises a wear layer, a first backing layer and a second backing layer.
The co-extruded laminate may comprise a first colored polymer composition, a xe2x80x9cblackxe2x80x9d polymer composition and a third polymer composition.
The method of the first aspect of the invention where the laminate comprises two or three polymer compositions may be carried out using conventional co-extrusion techniques. When it is desired to change the color of the face ply, the formulation of the colored polymer composition fed to the extruder is changed to provide the desired new color. As a consequence, the color of the colored polymer layer in the co-extruded laminate steadily changes from that of the original colored composition through intermediate shades to that of the new polymer composition while polymer of the original color is flushed from the system. According to prior practices, this intermediately-colored laminate would require to be dealt with as waste material. According to the invention, however, it may be immediately used without additional processing as the second backing film in a resilient floor covering which sequentially comprises a wear layer, a first backing film and a second backing film. The intermediately-colored layer of the second backing film is preferably disposed towards the interior of the composite laminate floor covering, because the color of this portion of the floor covering is not critical. The invention thus offers appreciable advantages of simplicity of operation and cost in comparison with prior art techniques.
It will be appreciated that the first and second backing films in the floor covering and the third and fourth aspects of the invention are preferably of substantially the same thickness in order that intermediately-colored first backing film can be used conveniently as the second backing film.
The thickness of the wear layer in the floor covering of the third aspect of the invention is preferably in the range 50 to 1000 micron, more preferably 250 to 750 micron. The thickness of the decorative printed patterned layer, if one is used, is preferably in the range 25 to 125 micron. The thickness of the backing layer may be in the range 1 to 4 mm, often 1.5 to 3 mm. Thus, the thickness of the first and second backing films may each be in the range 0.5 to 2 mm, often to 1.5 mm. The thicknesses of the two laminae constituted by the colored and the black polymer compositions in the backing film of the invention may be the same or different. For example, the colored lamina may be about 250 micron thick and the black lamina may be about 650 micron thick. It will be recognized that the thicknesses of these various films, layers and laminae are within the choice of the designer and producer of the floor covering, and are not markedly critical to the practice of the invention.
Preferably when the color of the face ply is changed in a resilient floor covering having at least one backing layer the method comprises the steps of:
(i) co-extruding a first polymer composition, a xe2x80x9cblackxe2x80x9d polymer composition and a third polymer composition to form a laminate to serve as a first backing film;
(ii) changing the formulation of the third polymer composition to provide a new color prior stopping the supply of color to the formulation of the first polymer composition whereby the color of the third polymer composition is well established before the color of the first colored polymer composition is changed; and
(iii) turning the co-extruded laminate over such that the third polymer composition forms the colored face ply layer.
Adding color pigment to the composition of the first or third polymer composition increases the cost of the laminate, so we do not want to run colored first and third layers simultaneously always, but we do want to have a length of run where there are good colored first and third layers (different colors) so that we can use the third layer of the laminate as the face ply before we stop coloring the first layer so there is no, or greatly reduced, amount of laminate which cannot be used as face ply with one of its first or third layers next to the wear layer.
The method of the first aspect of the invention where the laminate comprises three polymer compositions may be carried out using conventional co-extrusion techniques. When it is desired to change the color of the face ply, the formulation of the third polymer composition fed to the extruder is changed to provide the desired new color prior to the emptying of the supply of the formulation of the first colored polymer composition. As a consequence, the color of the third polymer layer in the co-extruded laminate is well established before the color in the first colored polymer composition runs out. According to the invention, the complete co-extruded laminate can be turned over such that the third polymer composition forms the colored face ply layer and the first colored polymer composition forms the layer beneath the black polymer composition layer.
It will be appreciated that the first and third polymer composition are preferably of substantially the same formulation with the exception of their color in order that the third polymer layer and the first colored polymer layer can be interchanged.
To enable the first and third lamina to be interchangeable when the film is turned over it is desirable to have the same amount of filler in each of the first and third polymer compositions. However, having a high filler content, such as 70% by weight in the first and third polymer compositions can cause the film to curl. In an embodiment of the invention the backing film may be extruded with filler contents of 70% by weight in the first polymer composition and 50% by weight filler in the third polymer composition to overcome the problem of curl. When the color of the third lamina is changed the filler content may be changed such that when the tile is turned over, so that the third lamina forms the first colored lamina, the third lamina has a higher filler content. The filler content of the first polymer composition may be reduced when the filler content of the third polymer composition is increased to avoid curl of the backing layer.
Filler can also be introduced into the second polymer composition to increase adhesion to the first and third polymer composition.
A second backing layer of substantially the same thickness as the first may be provided.
The thickness of the wear layer in the floor covering of the seventh aspect of the invention is preferably in the range 50 to 1000 micron, more preferably 250 to 750 micron. The thickness of the decorative printed patterned layer, if one is used, is preferably in the range 25 to 125 micron. The thickness of the backing layer may be in the range 1 to 4 mm, often 1.5 to 3 mm. Thus, the thickness of the first and second backing films may each be in the range 0.5 to 2 mm, often 0.75 to 1.5 mm. It will be recognized that the thicknesses of these various films, layers and laminae are within the choice of the designer and producer of the floor covering, and are not markedly critical to the practice of the invention.
The polymer compositions of the backing films of the invention and of the floor coverings containing them described hereinabove may be any of those known as suitable for the manufacture of floor coverings, although it will be understood that the polymer compositions used in the backing films must be susceptible of extrusion. Preferred polymer compositions for use in the backing films include compositions based on ethylene/vinyl acetate or ethylene/alkyl acrylate, for example methyl or butyl acrylate, copolymers. These polymer compositions generally comprise at least 10, preferably at least 20, percent by weight total fillers and pigments. These polymer compositions are preferably highly-filled polymer compositions which contain at least about 50 percent, preferably at least about 60 percent, often about 65 percent, by weight of one or more fillers, for example calcium carbonate, hydrated aluminum oxide or kaolin. The polymer compositions may contain up to about 75 percent by weight filler. A polymer composition for use in a backing film, including a colored polymer composition for use in a face ply, may contain about 5 to about 10 parts by weight of a binder polymer per 100 parts by weight (parts per hundred, phr) of the polymer on which the composition is based. Suitable binder polymers include ethylene/alkyl acrylate/maleic anhydride terpolymers. Such a binder polymer may permit the incorporation of high proportions of filler than can be otherwise achieved and may also serve to promote adhesion between films. A face ply composition contains a pigment in addition to any filler; for example it may contain 1 to 20 phr, often about 10 phr, of a white pigment such as titanium dioxide. A xe2x80x9cblackxe2x80x9d polymer composition for use in a backing film generally contains 1 to 5 phr, often about 3 phr, of a black pigment such as carbon black.
The invention provides in a sixth aspect a method of making floor tiles comprising:
(i) taking the co-extruded laminate of the present invention; and
(ii) cutting the laminate into suitable shapes.
The invention provides in a seventh aspect a method of laying a resilient floor covering comprising:
(i) securing the tiles of the sixth aspect to the floor of a room; and
(ii) polishing the tiles to provide a finish.
Preferably the tiles are secured to the floor by an adhesive.
Preferably the tiles are polished with a wax or silicone based polish.
It has been observed that polymer compositions containing high levels of pigment and filler, for example more than about 40 percent by weight, may suffer from the problem of die lip build-up when they are extruded. Small quantities of the highly-filled polymer composition are diverted at the point of extrusion from the main body of the film and adhere to the face of the die along the edges of the lips. This built-up material may be degraded by exposure to continual hot conditions. It may ultimately become detached from the die lips and adhere to the film, becoming embedded in the film when it is passed between polishing rollers. This results in the production of low quality film.
The invention accordingly provides in an eighth aspect a method of manufacturing a film for incorporation as a backing layer in a resilient floor covering, characterized in that (a) a colored first polymer composition containing not more than about 30 percent by weight total pigment and filler, (b) a xe2x80x9cblackxe2x80x9d second polymer composition, and (c) a third polymer composition containing not more than about 30 percent by weight total pigment and filler are co-extruded to form a film laminate for use as the backing layer. The colored first polymer composition may be of any color, including black.
The method of the ninth aspect of the invention has the advantage that the backing film is produced as a sandwich comprising a highly-filled core between less heavily-filled outer lamina. The problem of die lip build-up is thus avoided. The ninth aspect of the invention can be used in combination with any preceding aspect of the invention, i.e., a three-ply backing film may be made in accordance with it.
The invention provides in a tenth aspect a film suitable for incorporation as a backing layer in a resilient floor covering, characterized in that it is a co-extruded laminate of (a) a colored first polymer composition containing not more than about 30 percent by weight total pigment and filler, (b) a xe2x80x9cblackxe2x80x9d second polymer composition, and (c) a third polymer composition containing not more than about 30 percent by weight total pigment and filler.
The invention provides in an eleventh aspect a resilient floor covering comprising a wear layer and a backing layer, characterized in that the backing layer comprises a film according to the tenth aspect of the invention. The wear layer is transparent or translucent. The floor covering preferably additionally comprises a printed patterned layer interposed as decorative layer between the wear layer and the film.
The invention provided in a twelfth aspect a method of manufacturing a resilient floor covering, including the steps of:
(i) co-extruding (a) a colored first polymer composition containing not more than about 30 percent by weight total pigment and filler, (b) a xe2x80x9cblackxe2x80x9d second polymer composition and (c) a third polymer composition containing not more than about 30 percent by weigh total pigment and filler to form a backing film laminate; and
(ii) laminating together a transparent or translucent wear layer and the backing film laminate, whereby the colored first polymer composition is visible through the wear layer.
The colored first polymer composition may be based for example on an ethylene/alkyl acrylate copolymer. It generally contains about 10 to about 30, often about 20, percent by weight total fillers and pigments. A white composition may contain 1 to 20, often about 10, percent by weight titanium dioxide. A black composition may contain 1 to 5, often about 3, percent by weight carbon black. The fillers used in the colored first polymer composition may be any of the fillers mentioned above for the highly filled polymer compositions. The thickness of the colored first lamina is preferably in the range about 10 to about 150 micron, often about 50 micron. The xe2x80x9cblackxe2x80x9d second polymer composition may be as described hereinabove for highly-filled black polymer compositions, and the thickness of the corresponding lamina may be about 500 to about 1000 micron. The third polymer composition may be based for example on polyethylene or other suitable polymers and copolymers. It generally contains fillers and pigments as described for the colored first polymer composition and is often black. The thickness of the third lamina may be in the range about 10 to about 150 micron, often about 20 micron.
If desired, any of the composite backing films of the invention may include an adhesive interlayer between the adjacent laminae, in conventional manner for co-extruded films.
The wear layer of the floor coverings of the invention may be of known type, and generally comprises one or more calendered or extruded films, which are preferably transparent or translucent. Preferred materials for manufacture of the wear layer include ionomers of the SURLYN type (trademark of DuPont). Such materials are described in U.S. Pat. Nos. 3,264,272 and 3,322,734. The floor coverings of the invention may be used in sheet or tile form.